Reservoir heterogeneity is one of the main factors that impact distribution of remaining oil.Intralayer

interlayer and plane-layer heterogeneities exist in the upper Guantao Formation in the 7

th

block west of Gudong oilfield.Plane-layer heterogeneity is mainly controlled by sedimentary facies zones and distribution of sandbodies.Interlayer heterogeneity is mainly affected by the thickness of single sandbody and sand-shale ratio.Intralayer heterogeneity is mainly associated with intraformational beds and intracyclothems.Remaining oil is relatively rich in sandbodies with relatively poor poroperm characteristics

such as in the lower part of interbeds and on the top of positive cyclothems.In addition

sandbodies with limited distribution on the periphery of channel sands and in abandoned channels are also rich in remaining oil.